Technically, it is possible, but registering usual GPIO controllersin arch_initcall feels not quite right approach in the first place(and, btw, it won't work most of the time, because even early driversdo not register itself earlier than subsys_initcall).

And arch gpio controllers (like QE GPIO) are usually device-less,and they use of_mm_gpiochip_add(), so we fully control them.

Plus I don't see any reason why we couldn't moveof_gpio_notifier_init() into, say, postcore_initcall, if we everneed it.